Vehicular antenna with improved screening

ABSTRACT

vehicle antenna ( 1 ) comprising a satellite signal amplifier and/or receiver circuit ( 2 ) assembled on a board ( 6 ), an antenna base ( 3 ) for support of said board ( 6 ), applicable to the structure of a vehicle (A), connection means ( 7 ) to mechanically fix said board ( 6 ) to said antenna base ( 3 ), a coaxial cable ( 8 ) that connects the satellite signal amplifier and/or receiver circuit ( 2 ) to a receiving apparatus installed in the vehicle (A). Between the antenna base ( 3 ) and the board ( 6 ) electro-conductive elastic means ( 13 ) are interposed to achieve electricity continuity between the antenna base ( 3 ) and the metallic braiding ( 8   b ) of the coaxial cable ( 8 ) when the connection means ( 7 ) fix the board ( 6 ) to the antenna base ( 3 ).

This application is a 371 of PCT/EP 03/11375 Oct. 14, 2003.

FIELD OF THE INVENTION

The invention concerns a vehicular antenna with improved screening forreceiving satellite signals and telephone communications.

BACKGROUND OF THE INVENTION

It is known that to receive satellite signals and to enable telephonecommunications from vehicles the so-called “combined” antennas are used,provided with a single antenna base applied to the vehicle structure,which supports a satellite signal amplifier and/or receiver circuit anda monopole for telephone communications.

One of the most important characteristics of these combined antennas istheir ability to guarantee the correct reception of the satellite signaleven during telephone communications.

However, it is known that during telephone communications the signalwhich is sent forth is partly picked-up by the satellite signalamplifier and/or receiver and this affects the good reception of thesignal itself by the satellite navigation system installed in the motorvehicle.

To this purpose, specially designed techniques set the decoupling valuebetween the telephone signal and the satellite signal and therefore theysubstantially define the maximum acceptable power of the interferingsignal that can be absorbed by the satellite amplifier and/or receiver.

To obtain the decoupling of the antennas, it is necessary to insulatethe satellite signal amplifier and/or receiver circuit, so as to preventthe entry of the signal coming from the telephone antenna.

According to a known technique, the problem is solved by encapsulatingthe satellite signal amplifier and/or receiver inside a metal casingthat can be electrically insulated or connected to the structure groundthrough contact.

The patent application no. EP 0 989 629 describes an example of thiskind, that is, a vehicular antenna, a portion of which is of GPS (GlobalPositioning System) type for satellite communications, while the otherportion is a telephone antenna for telephone communications, saidvehicular antenna being extremely compact.

According to another known technique, the problem can be solved byfixing the satellite signal amplifier and/or receiver to the base of theantenna, which is suitably shaped, so as to eliminate any openingthrough which the telephone transmission signal can enter and interferewith the satellite signal amplifier and/or receiver.

Said types of insulation, however, present the drawback of being ratherexpensive to produce.

Furthermore, the coaxial cable coming from the satellite navigationsystem installed in the motor vehicle connects to the satellite signalamplifier and/or receiver circuit passing through said suitable shapingmade on the base of the antenna.

Through this shaping the signal emitted by the telephone antenna canreach the satellite signal amplifier and/or receiver circuit and only bymeans of perfect welding either on the base or on the casing, it ispossible to obtain an optimal closing of the cable passage area andtherefore an optimal ground contact.

BRIEF SUMMARY OF THE IVENTION

The present invention aims to overcome the drawbacks listed above.

In particular, one of the main objectives of the invention is theimplementation of a vehicular antenna with improved screening, whosedegree of insulation from the electromagnetic waves of the satellitesignal amplifier and/or receiver circuit is better than that offered bycombined antennas of the known type.

Practically, the intention is to create a sort of physical barrier tothe electromagnetic waves of the telephone signal that may disturb thereception of the satellite signal.

Another objective of the invention is to simplify the constructivestructure of the vehicular antenna, in such a way as to reduce itsproduction cost compared to that of the known equivalent antennas.

More precisely, the aim is to guarantee a suitable ground contact incorrespondence with the coaxial cable passage area, eliminating anywelding between the coaxial cable and the base of the antenna or a metalcasing.

The objectives mentioned above are achieved through the implementationof a vehicular antenna that, according to the main claim, comprises:

-   -   at least one satellite signal amplifier and/or receiver circuit        assembled on a board provided with at least one earth plane;    -   an antenna base to support said board, attachable to the vehicle        structure;    -   connection means suitable for mechanically fixing said board to        said antenna base and for achieving electricity continuity        between said antenna base and said at least one earth plane of        said board;    -   a coaxial cable that connects said satellite signal amplifier        and/or receiver circuit to a receiving apparatus installed in        said motor vehicle,        and is characterised in that it comprises electro-conductive        elastic means interposed between said antenna base and said        board, and suited to constitute a barrier to prevent the        interference of the telephone communication signal with the        satellite communication signal and to achieve electricity        continuity between said antenna base and the metallic braiding        of said coaxial cable when said connection means fix said board        to said antenna base.

According to the preferred embodiment that is described here below, themeans for the connection of the board to the antenna base are rivets andthe electro-conductive elastic means consist of a metal foil shaped insuch a way as to make it elastic.

According to other embodiments, the conductive elastic means consist ofa shaped body made of an elastomer loaded with conductive elements.

To advantage, the antenna object of the invention, compared to knownantennas, produces greater decoupling between the satellite signalamplifier and/or receiver and the monopole for telephone communications.

Consequently, it is less sensitive to interferences.

Another advantage offered by the antenna object of the invention isrepresented by the fact that it doesn't require welding operations andtherefore it is quicker, simpler and less expensive to construct thanequivalent known antennas.

BRIEF DESCRIPTION OF THE DRAWINGS

The objectives and advantages described above will be highlighted ingreater detail in the description of a preferred embodiment of theinvention, with reference to the attached drawings, wherein:

FIG. 1 is an axonometric exploded view of the antenna object of theinvention;

FIG. 2 is an exploded longitudinal sectional view of the antenna objectof the invention;

FIG. 3 is a longitudinal sectional view of the antenna of FIG. 2 whenassembled;

FIG. 4 is an axonometric view of a detail of FIG. 3;

FIG. 5 is an exploded view of a detail of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The vehicular antenna object of the invention is represented in Figuresfrom 1 to 3, where it is indicated as a whole by 1.

It can be observed that it comprises a satellite signal amplifier and/orreceiver circuit, indicated as a whole by 2, that is supported by anantenna base 3 attachable to the structure of a vehicle A.

Hereinafter the amplifier and/or receiver circuit will be indicatedsimply with the expression “receiver circuit”.

Preferably, but not necessarily, a shaped gasket 4 is interposed betweenthe vehicle A and the antenna base 3, while a protection cover 5overlaps and is fixed onto the base 3 itself.

The satellite signal receiver circuit 2 is assembled onto a board 6provided with an earth plane 6 a visible in particular in FIGS. 2 and 3,which serves to achieve electricity continuity with the antenna base 3,made of an electrically conductive material, when the receiver circuit 2is fixed to it through connection means that consist of rivets 7.

It is evident that the rivets 7 can be replaced by other fixing means,e.g. screws or other means.

The board 6 supports all the electric/electronic components that make upthe satellite signal receiver circuit 2, which, by means of a coaxialcable indicated as a whole by 8, is connected to a receiving apparatus,not represented in the figures and installed on the vehicle A.

In particular, it can be observed that the coaxial cable 8 has theelectricity conductor 8 a electrically connected to the satellite signalreceiver circuit 2 and the external metallic braiding 8 b electricallyconnected, preferably through welding, to the earth plane 6 a.

When the board 6 is assembled onto the antenna base 3, it rests on anannular edge 9 projecting from the base 3 itself, in which there is anhousing, indicated by 10 in FIG. 1. This ensures the passage of thecoaxial cable 8, which is incorporated into the shaped body 11, where itis substantially bent at 90°.

A monopole 12, connected to an apparatus for telephone communicationsthrough a coaxial cable 12 a installed in the vehicle A, is also appliedto the antenna base 3.

It is mainly through the housing 10 that the satellite signal receivercircuit 2 can receive radiofrequency signals coming from the monopole12.

According to the invention, in order to avoid the entry of signals fromthe monopole 12 to the satellite signal receiver circuit 2,electro-conductive elastic means, indicated as a whole by 13, areinterposed between the antenna base 3 and the board 6 and are also meantto achieve electricity continuity between the antenna base 3 andmetallic braiding 8 b of the coaxial cable 8, when the connection means7 fix the board 6 to the antenna base 3.

In particular, it can be observed in FIGS. 4 and 5 that theelectro-conductive elastic means 13 are constituted by anelectro-conductive shaped foil 14 that is positioned in the housing 10of the annular edge 9, in which a first contact surface 15 with theantenna base 3 and a second contact surface 16 with the metallicbraiding 8 b arranged on the outside of the conductor 8 a of the coaxialcable 8 are defined.

More specifically, the surfaces 15 and 16 are plane concurrent surfacescreating a dihedral angle 17 with transversal V-shaped profile, so as togive elasticity to the foil 14.

In this way, the electro-conductive shaped foil 14 prevents thepropagation of the electromagnetic waves of the telephone signal comingfrom the monopole 12.

The telephone signal and the satellite signal flowing in the coaxialcable 8 are thus separated.

It is clear, therefore, that the use of the above mentioned shaped foil14 improves the degree of insulation from electromagnetic waves of theamplifier and/or receiver circuit 2 of the satellite signal.

Furthermore, said amplifier and/or receiver circuit 2 is screened withno need to carry out weldings in correspondence with the passage zonesof the coaxial cable 8 into the housing 10, thus simplifying theconstructive structrure of the antenna 1 in its whole.

To guarantee the stability of the shaped foil 14 on the inside of thehousing 10, the first contact surface 15 is provided with lateralindentations 18, 19, which can be observed in FIG. 5, which receive theannular edge 9 projecting from the antenna base 3, when the conductivefoil 14 is inserted into the housing 10.

It can also be observed that at the end 18 a, 19 a of each one of thelateral indentations 18, 19, an element 18 b, 19 b projects from thefirst surface 15, which, as can be seen in FIG. 4, is positioned alongthe edges 10 a, 10 b that delimit the housing 10, thus guaranteeing thestability of the insertion.

From an operative point of view, to assemble the antenna, the shapedfoil 14 is inserted into the housing 10 and then the satellite signalreceiver circuit 2 is coupled to the antenna base 3, fixing the edges ofthe board 6 to the annular edge 9, so that the second surface 16 of theconductive shaped foil 14 is forced against the braiding 8 b of thecoaxial cable 8.

The presence of the foil 14 achieves the double purpose of closing thehousing 10 and of improving the ground contact with the earth plane 6 aof the board 6, thus contributing to the improvement of the degree ofinsulation of the satellite signal receiver circuit 2 from externalsignals, especially from those coming from the monopole 12 for telephonecommunications.

The electro-conductive shaped foil 14 can be in any metallic material,provided that it is a conductive material, or even in a non-metallicmaterial, for example elastomer loaded with conductive elements.

It is clear, therefore, on the basis of the above description, that theantenna object of the invention achieves the purpose of improving theinsulation of the satellite signal receiver circuit 2 from externalradiofrequency signals.

The aim to make the reception of satellite signals more reliable and ofhigher quality even and above all during telephone communications isthus achieved. Furthermore, the aim to produce an antenna that is morecost-effective is also achieved, owing to the fact that the screeningand the connection welding of the satellite signal receiver circuit 2 tothe antenna base 3 are eliminated.

Upon implementation of the antenna object of the invention the shape ofthe conductive elastic means 13 and of their housing 10 in the antennabase 3 may be varied.

It is understood that these variants and other possible variants thatare not described or illustrated herein are all protected by the presentpatent, provided that they are carried out in compliance with thefollowing claims.

1. Vehicular antenna comprising: at least one satellite signal amplifierand/or receiver circuit assembled on a board provided with at least oneearth plane; an antenna base for the support of said board, applicableto the structure of a vehicle; connection means suitable formechanically fixing said board to said antenna base and for achievingelectricity continuity between said antenna base and said at least oneearth plane of said board; a coaxial cable that connects said satellitesignal amplifier and/or receiver circuit to a receiving apparatusinstalled in said vehicle, an electro-conductive elastic meansinterposed between said antenna base and said board, suited toconstitute a barrier to prevent the interference of the telephonecommunication signal with the satellite communication signal and toachieve electricity continuity between said antenna base and a metallicbraiding of said coaxial cable when said connection means fix said boardto said antenna base.
 2. Vehicular antenna according to claim 1, furthercomprises a monopole for receiving/transmitting telephone signals,provided with a respective coaxial cable for the connection to atelephone apparatus installed in said vehicle.
 3. Vehicular antennaaccording to claim 2, wherein said electro-conductive elastic means arepositioned into a housing obtained in an annular edge projecting fromsaid antenna base on which said board rests.
 4. Vehicular antennaaccording to claim 2, wherein said electro-conductive means consist ofan electro-conductive shaped foil, in which a first contact surface withsaid antenna base and a second contact surface with said metallicbraiding are defined, said surfaces being concurrent and forming adihedral angle with transversal V-shaped profile.
 5. Vehicular antennaaccording to claim 2, wherein said connection means are rivets. 6.Vehicular antenna according to claim 2, wherein said connection meansare screws.
 7. Vehicular antenna according to claim 1 wherein saidelectro-conductive elastic means are positioned into a housing obtainedin an annular edge projecting from said antenna base on which said boardrests.
 8. Vehicular antenna according to claim 7, wherein saidelectro-conductive elastic means are made of elastomer loaded withconductive elements.
 9. Vehicular antenna according to claim 7, whereinsaid electro-conductive means consist of an electro-conductive shapedfoil, in which a first contact surface with said antenna base and asecond contact surface with said metallic braiding are defined, saidsurfaces being concurrent and forming a dihedral angle with transversalV-shaped profile.
 10. Vehicular antenna according to claim 1 whereinsaid electro-conductive means consist of an electro-conductive shapedfoil, in which a first contact surface with said antenna base and asecond contact surface with said metallic braiding are defined, saidsurfaces being concurrent and forming a dihedral angle with transversalV-shaped profile.
 11. Vehicular antenna according to claim 10, whereinsaid electro-conductive foil is metallic.
 12. Vehicular antennaaccording to claim 10, wherein said first contact surface is providedwith lateral indentations that receive said projecting annular edge whensaid electro-conductive shaped foil is inserted into said housing. 13.Vehicular antenna according to claim 12, wherein at the end of each oneof said lateral indentations, an element projects from said firstcontact surface.
 14. Vehicular antenna according to claim 10, whereinsaid contact surfaces are plane surfaces.
 15. Vehicular antennaaccording to claim 1, wherein said connection means are rivets. 16.Vehicular antenna according to claim 1, wherein said connection meansare screws.